a) = \(\dfrac{124}{3} . \dfrac{5}{6} - \dfrac{56}{5} . \dfrac{5}{6} - \dfrac{1}{2}\)
= \(\dfrac{620}{18}\) . \(\dfrac{5}{6} - \) \(\dfrac{280}{30}\) - \(\dfrac{1}{2}\)
= 3100/180 - 530/60
= 755/45 - 265/30
= ....
a,\(41\dfrac{1}{3}.\dfrac{5}{6}-11\dfrac{1}{5}.\dfrac{5}{6}-\dfrac{1}{2}\)
\(=\dfrac{5}{6}.\left(41\dfrac{1}{3}-11\dfrac{1}{5}\right)-\dfrac{1}{2}\)
\(=\dfrac{5}{6}.\dfrac{452}{15}-\dfrac{1}{2}\)
\(=\dfrac{226}{9}-\dfrac{1}{2}\)
\(=\dfrac{443}{18}\)
b,\(\dfrac{-5}{7}.\dfrac{5}{8}-\dfrac{5}{7}.\dfrac{3}{8}+\dfrac{5}{7}\)
\(\left(\dfrac{-5}{7}.\dfrac{5}{8}-\dfrac{5}{7}.\dfrac{3}{8}\right)+\dfrac{5}{7}\)
\(\left(\dfrac{-5}{7}.\left(\dfrac{5}{8}-\dfrac{3}{8}\right).4\right)+\dfrac{5}{7}\)
\(\left(\dfrac{-5}{7}.\dfrac{1}{4}.4\right)+\dfrac{5}{7}\)
\(\dfrac{-5}{7}+\dfrac{5}{7}=0\)
